Blood oxygenator with heat exchanger



Sept. 23, 1969 D. A. RAIBLE ET AL 3,468,631

BLOOD OXYGENATOR WITH HEAT EXCHANGER Filed June 21, 1965 2 Sheets-Sheet l INVENTORS DONALD A. RA|BLE BY 1 DONALD J. BENTLEY RICHARD A. DEWALL Attorney S p 1969 D. A. RAIBLE ET AL 3,468,631

BLOOD OXYGENATOR WITH HEAT EXCHANGER Filed June 21, 1965 2 Sheets-Sheet :3

INVENTORS 44 DONALD A. RAI BLE DONALD J. BENTLEY RICHARD A. DEWALL Attorney United States Patent U.S. CI. 23-2585 14 Claims ABSTRACT OF THE DISCLOSURE A unitary blood oxygenator and heat exchanger having a rigid casing, an oxygenator chamber having batlle means and being in the upper part of the casing, a settling chamber separate from, and in communication with, the oxygenator chamber, and a heat exchanger in communication with the settling chamber by means of a thin, elongate 0t.

This invention relates to a blood oxygenator to perform the lung function of a heart-lung machine.

In certain operations or other treatments of the body, it is necessary to establish an extracorporeal circulation system for temporarily assuming the functions of the heart and lungs of the patient. In such a system the lung function is performed by an oxygenator. It may also be desired to raise or lower the temperature of the blood in the extracorporeal system or to do both in dilferent parts of the system.

Heretofore, heat exchangers for this purpose have generally been made as separate units which were connected by tubing with other components of the system. This has been undesirable because of the time involved in connecting up the components and getting the system into operation, because of the large amount of priming blood required to fill the system, because of the problem of sterilizing all the equipment and for other reasons.

Objects of the present invention are, therefore, to provide an improved bubble-type oxygenator, to provide an improved heat exchanger, to provide an oxygenator and heat exchanger combined in a single compact unit, to provide a unit of the type described which is economical to manufacture and disposable after a single use, to provide such a unit having a relatively small priming volume, to provide such a unit of substantially rigid construction so as to maintain desired configurations and dimensions of inside passages and chambers and to provide such a unit having a translucent casing so that the flow of blood therewithin may be observed.

The present oxygenator and heat exchange unit has a stifi casing formed by a pair of right and left vacuum molded plastic shells which are secured together and contain elements of the apparatus in chambers formed by cavities in the molded shells. In this way the dimensions and configurations of the internal chambers and passages may be accurately controlled to establish a desired regimen of flow of the blood, obtain quick response from the heat exchanger and minimize the priming volume.

The translucent property of the plastic shells permits continuous observation of the blood flow through the unit. The unit is readily set up for operation with a minimum of connections and other preparatory work and the amount of priming blood is further reduced by the close association of the heat exchanger with the oxygenator in a common unit. By making the unit disposable, it never has to be sterilized after use.

The invention will be better understood and the foregoing and other objects and advantages will become apparent from the following description of the preferred em- "ice bodiment illustrated in the accompanying drawings. Various changes may be made in the details of construction and arrangement of parts and certain features may be used without others. All such modifications within the scope of the appended claims are included in the invention.

In the drawings:

FIGURE 1 is a perspective view of an oxygenator and heat exchanger unit embodying the principles of the invention;

FIGURE 2 is a side elevation view with one of the casing shells and other parts broken away;

FIGURE 3 is a view on the line 3-3 of FIGURE 2;

FIGURE 4 is a view on the line 4-4 of FIGURE 2;

FIGURE 5 is a view on the line 55 of FIGURE 2; and

FIGURE 6 is a view on the line 6-6 of FIGURE 2.

The oxygenator and heat exchanger parts are contained within and supported by a pair of complementary, vacuum molded, plastic shells A and B which form left and right halves of an external casing. These two shells are of similar configuration and mate together in a joint plane which extends vertically through the mid-section of the device. At the top the shells have inclined semi-cylindrical complementary cavities which form an inclined cylindrical oxygenating chamber 10. At the bottom the shells have inclined semi-cylindrical complementary cavities which form a cylindrical heat exchange chamber 11.

Between these two cylindrical chambers there is a conical settling and debubbling chamber 12 similarly formed by complementary cavities in the two shells. Smaller complementary cavities in the two shells form a port 13 from the bottom of the oxygenator chamber 10 to the top of settling chamber 12 and an elongated slot-shaped port 14 from the bottom of settling chamber 12 to heat exchange chamber 11. Each of these chambers and ports is contained half in the shell A and half in the shell B.

The shells A and B are made of a suitable, preferably translucent, non-toxic, plastic material capable of being vacuum molded and capable of being united by heat seals or chemical bonding as by an epoxy resin or compatible solvent. For bonding purposes, the marginal portions of the shells and intermediate portions between the chambers are disposed in a common medial plane as indicated by the line 15 in FIGURES =3 and 6. Thus, when the two shells are mated together and bonded, the abovementioned chambers and ports are entirely enclosed except for certain openings which will be described.

The shells are sufliciently still that the molded contours of the cavities forming the described chambers and ports are self-sustaining and do not lose their shape by collapsing, bulging or sagging under the weight of the internal component and the blood which partially fills the chambers in use. In use, the casing is supported in upright position by means of hanger holes 16 with the back edge 17 approximately vertical.

The lower end of oxygenator chamber 10 is closed at the front edge 18 of the casing by a plastic inlet plate 20 having a cylindrical peripheral edge 21 bonded and sealed to the shells A and B. Mounted on a boss 19 on the inner side of plate 20 is a plastic tube 22 forming a cylindrical bubble chamber concentric with the chamber 10. Tube 22 is closed at its upper end and is provided with a pair of outlet slots 23 on opposite sides of its distal end. A small drain opening 23a is also provided. By tipping the casing clockwise in FIGURE 2, the blood may be drained out of the bubble chamber through this opening when desired. The bubble chamber is supplied with venous blood through an inlet connection 24 in plate 20.

Also mounted on the inside of plate 20 is a plastic bubble tube or plate having a closed upper end and a perforated side wall 26. This bubble tube extends only a short distance into the lower end of bubble chamber 22 and is supplied by an oxygen inlet connection 27. As shown in FIGURE 1, inlet connection 24 may be made in the form of a Y for connection with two different sources of venous blood if desired. A side connection 27a may also be provided for taking blood samples at this point if desired. The bubble chamber may be furnished with inclined perforated baflles 28 to direct the flow of the blood-oxygen mixture.

Bubble chamber 22 is surrounded with a layer of coarse knit mesh 30 of polypropylene plastic or other suitable material impregnated with a non-toxic, anti-foam material such as medical silicone anti-foam which is well-known in the trade. The mesh material is confined by a porous cover 31 preferably of nylon fabric. This cover is secured to the lower end portion of tube 22 by a drawstring 32 so that all of the blood must pass through it. The mesh layer 30 is cylindrical and only slightly smaller in diameter than chamber 10 and is of a construction that provides suitable filtering ability.

The upper end of chamber 10 is vented at its highest point by a vent passage 35 which connects with an external vent opening 36 at the highest point in the casing adjacent the rear edge 17. Extending directly downward from vent opening 36 is another vent passage 37 which communicates with the highest point in settling chamber 12. A plurality of external ports and connector fittings 38 communicate with vent passage 37 through back edge 17 of the casing.

Heat exchange chamber 11 contains a cylindrical metal can 40 for heating or cooling water. The beaded inner end of this can is retained by an annular ridge 41 in the plastic shells and the side wall is clamped between the surfaces of the shell cavities which form chamber 11. The outer end of the can is sealed at 42 to the walls of the shell cavities. The shell cavities are vertically grooved to provide shallow channels 45 around the can. The blood enters chamber 11 through slot port 14 directly over the top side of can 40 and flows around opposite sides of the can in thin films through channels 45 to an inclined bottom sump passage.

FIGURE 2 shows only a small portion of the outside of shell B at the lower right corner of the casing, the rest of shell B being broken away to show the internal structure and the inside of shell A. The hatching on shell A designates the broken bond between the two shells and indicates the extent of the bonded areas in joint plane 15.

Temperature controlled water is admitted into the front end of can or tank 44 through a bottom inlet connection 52. Water leaves the can in continuous circulation through an outlet connection 59 and tube 51 which takes Water from the top rear of the can. Oxygenated and temperature controlled blood leaves the sump passage 44 through an outlet connection 55 which may also take the form of a Y to provide two separate supplies of oxygenated blood. This connection may be equipped with a thermometer or thermocouple tube 56 for monitoring the temperature of the outlet flow.

When the casing is hung in vertical position as shown in FIGURE 2 and the various external connections are established as described, venous blood will flow continuously through inlet connection 24 into the inclined bubble chamber 22 and oxygen will discharge continuously into the blood from bubble tube 25. The rate of flow of blood depends upon the size of the patient. In order to maintain quick response of the heat exchanger, the blood level in settling chamber 12 preferably should not fall below the line 61 since at a lower lever the upper end portion of the water tank 40 is not exposed to contact with the blood.

The present construction allows for a variation in flow rates to accommodate patient sizes from infants to large adults. For intermediate or average rates of flow, the

precise vertical positioning of the casing is not critical. The blood level in the various chambers and the flow through channels 45 is readily observable through the translucent material of the shells.

The connector fittings 33 provide for different chemical treatments of the blood as may be necessary in some cases. Vent opening 36 allows the escape of carbon dioxide and excess oxygen from both oxygenator chamber 10 and settling and debubbling chamber 12. This vent opening is made rather large and funnel-shaped to facilitate the addition of a large amount of blood quickly if it should be needed in an emergency. From the foregoing description it will be appreciated that the size and arrangement and close communication of the various chambers all contribute to keep the priming blood to a minimum.

Having now described our invention and in what manner the same may be used, what we claim as new and desire to protect by Letters Patent is:

1. A blood oxygenator comprising a shell of relatively stifl? material, including cavities defining an oxygenator chamber including blood inlet means and blood and gas outlet means and a bubble chamber therein; said bubble chamber including an upwardly inclined bubble tube in the interior of the oxygenator chamber with oxygen outlet means in said bubble tube; defoaming means spaced from, and surrounding, said bubble tube; and an oxygen inlet connection to said bubble tube with baffle means in said oxygenator chamber spaced above said bubble tube.

2. The oxygenator of claim 1 wherein the batfie means is perforate.

3. The oxygenator of claim 1 wherein the baffle means are inclined relative to the path of fluid flow in the oxygenator chamber.

4. The oxygenator of claim 3 wherein the bafile means are oriented to extend generally horizontally during use.

5. A blood oxygenator comprising: a generally rigid case having cavities defining an oxygenator chamber and a heat exchange chamber in communication with each other the oxygenator chamber having blood and oxygen inlet means and gas outlet means; a cylindrical heat exchanger in the heat exchange chamber defining in combination with the casing, a thin, divided annular blood flow jacket, means for heating said heat exchange chamber; and blood outlet means in said heat exhange chamher.

6. The blood oxygenator of claim 5 wherein the blood flow jacket is divided into a plurality of channels.

7. The blood oxygenator of claim 6 wherein the inner surface of the casing is provided with grooves which define said channels.

8. A blood oxygenator assembly comprising a generally rigid case having complementary cavities including first cavities defining an oxygenator chamber with blood and oxygen inlet means and blood and gas outlet means, second cavities defining a set- 'tling chamber separate from, and in communication with, said oxygenator chamber, and third cavities defining a heat exchange chamber in communication with said settling chamber and means for conducting a heat exchange medium to said heat exchange chamber.

9. The oxygenator assembly of claim 8 wherein the heat exchange chamber is in communication with the settling chamber by generally thin, elongate port means capable of producing a generally sheet-like flow of blood.

10. The oxygenator assembly of claim 8 wherein communication between the oxygenator chamber and the settling chamber is established through a narrow port at one end of the oxygenator chamber.

11. A blood oxygenator and heat exchanger comprising: a casing; an oxygenator chamber in the upper part of the casing having blood and oxygen inlet means and gas outlet means, said oxygenator chamber including means defining a trough at the bottom thereof for feeding blood in an inclined path to a port at the bottom of the oxygenator chamber; a debubbling chamber separate from, and below said oxygenator chamber and in communication therewith by means of the said port at the bottom of the oxygenator chamber; a heat exchange chamber below said debubbling chamber and in communication therewith, said heat exchange chamber having means for conducting a heat exchange medium toward and away from the chamber and including a liquid jacket closely spaced from a heat exchange element, and means communicating said debubbling chamber with said heat exchange chamber including means defining thin, elongated fluid passage from the bottom of the debubbling chamber in communication with said fluid jacket for dis charging a sheet-like flow of blood into said fluid jacket; and outlet means at the bottom of said heat exchange chamber.

12. The oxygenator of claim 11 wherein the casing comprises a pair of generally rigid mating shells having complementary cavities forming said chambers and ports.

13. The oxygenator of claim 11 wherein the heat exchange element has spaced shallow channel portions generally transverse to the extent of the elongate slot.

14. The oxygenator of claim 13 wherein the heat exchange element comprises a cylindrical tank positioned within said liquid jacket, the tank being provided with means for establishing communication with a source of temperature regulating medium.

References Cited UNITED STATES PATENTS MORRIS O. WOLK, Primary Examiner BARRY S. RICHMAN, Assistant Examiner US. Cl. X.R. 

